This invention relates to doors for containers, such as the cargo containers used with large aircraft. Two types of doors are presently in use, a solid door and a flexible door. Solid doors have been in use for some time, but have the disadvantage of a significantly greater weight and cost than the flexible doors. The flexible door is made of some type of sheet or woven fabric, and prior art designs for flexible doors are shown in U.S. Pat. Nos. 4,046,186 and 4,429,730. In the container cover of the U.S. Pat. No. 4,046,186, two reinforcing cables are diagonally fitted in the cover or door, and another peripheral cable fits into flanges in the door frame, with this cable being pulled tight by a ratchet to hold the door in place. However, the tensioning provided is not equal in both diagonal cables nor equal in the diagonal and peripheral cables. In the door or cover of the U.S. Pat. No. 4,429,730, cables in the door are pulled taut by a toggle type mechanism at each of the two lower corners. This design does not provide for any additional tensioning of the diagonally positioned cables after the door is in place in the door frame.
In another prior art design four cables or straps are positioned about the sides and bottom of the door and diagonally across the door, in two sets of two, with each set tensioned by a buckle, thereby requiring two buckles and two tensioning actions.
These prior art designs have various disadvantages. Those which provide no secondary tensioning of the cables positioned across the door opening are undesirable in that there is no way to pull the door flat after closure. This can be a particular problem when items loaded within the container shift during handling, often resulting in cargo falling outward when the door is opened with resultant damage to the cargo and/or to the cargo handler.
A disadvantage of the design with the two sets of cables and two buckles is that the cargo handler must separately tension each of the sets of cables after the door is closed, requiring additional effort and providing an opportunity for failure of the cargo handler to adequately tension both buckles.
Other disadvantages include the fact that load shifting during usage places stress on the cover making it difficult to release. Also, some designs with flexible doors require a heavy bottom horizontal member which sometimes causes damage to the container, the aircraft, and/or the personnel handling the container. By way of example, after a flexible door is released, the lower portion of the door is flipped upward to rest on the top of the container during unloading and loading. The damage may occur when the door bottom is not properly handled during this motion or when the door slides off of the top of the container.
It is an object of the present invention to provide a new and improved flexible door for a cargo container and the like which does not have the disadvantages discussed above. Another object of the invention is to provide such a door which requires only three cables and only one adjustable buckle.
It is a further object of the invention to provide such a flexible door which can be closed with a minimum of effort and which can then be tensioned both peripherally and diagonally by actuation of a single buckle mechanism, which buckle does not need to be disconnected and reconnected during use.
Other objects, advantages, features and results will more fully appear in the course of the following description.